LightSquared isn't the only entity posing a significant threat to the Global Positioning System. The Christian Science Monitor, in an exclusive interview with an Iranian engineer, reported that Iranians used a spoofing technique to make the drone "land on its own where we wanted it to, without having to crack the remote-control signals and communications."
According to the Monitor:
The techniques were developed from reverse-engineering several less sophisticated American drones captured or shot down in recent years, the engineer says, and by taking advantage of weak, easily manipulated GPS signals, which calculate location and speed from multiple satellites.
This kind of vulnerability isn't new. My colleague Bob Brewin reported similar problems with GPS last year.